泛型委托

using System;

namespace 泛型委托
{
    class Program
    {
        private delegate bool DelCompare(object o1, object o2);

        private delegate bool Compare<T>(T t1, T t2);
        static void Main(string[] args)
        {
            string[] strings = { "C#", "FrameWork", ".net" };
            int[] ints = { 1, 2, 3, 4, 5 };

            // 1. 普通方法
            string maxString = GetMaxString(strings);
            int maxInt = GetMaxInt(ints);
            Console.WriteLine(maxString);
            Console.WriteLine(maxInt);

            // 2. 委托方法
            // 比较麻烦，需要装拆箱
            object[] strings2 = { "C#", "FrameWork", ".net" };
            object[] ints2 = { 1, 2, 3, 4, 5 };
            maxString = (string)GetMax(strings2, CompareString);
            maxInt = (int)GetMax(
                ints2,
                delegate (object o1, object o2)
                {
                    // 拆箱
                    int i1 = (int)o1;
                    int i2 = (int)o2;
                    return i1 < i2;
                });
            Console.WriteLine(maxString);
            Console.WriteLine(maxInt);

            // 3. 泛型委托
            // 语法简单，性能高
            maxString = GetMaxT<string>(strings, (s1, s2) => { return s1.Length < s2.Length; });
            maxInt = GetMaxT<int>(ints, (i1, i2) => i1 < i2);
            Console.WriteLine(maxString);
            Console.WriteLine(maxInt);

            Console.ReadKey();
        }

        #region 普通方法

        private static string GetMaxString(string[] strings)
        {
            string max = strings[0];
            foreach (var s in strings)
            {
                if (max.Length < s.Length)
                {
                    max = s;
                }
            }

            return max;
        }

        private static int GetMaxInt(int[] ints)
        {
            int max = ints[0];
            foreach (var i in ints)
            {
                if (max < i)
                {
                    max = i;
                }
            }

            return max;
        }

        #endregion

        #region 委托方法

        private static object GetMax(object[] objects, DelCompare del)
        {
            object max = objects[0];
            foreach (var o in objects)
            {
                if (del(max, o))
                {
                    max = o;
                }
            }

            return max;
        }

        private static bool CompareString(object o1, object o2)
        {
            string s1 = o1.ToString();
            string s2 = o2.ToString();
            return s1.Length < s2.Length;
        }

        #endregion

        #region 泛型委托

        private static T GetMaxT<T>(T[] ts, Compare<T> compare)
        {
            T max = ts[0];
            foreach (T t in ts)
            {
                if (compare(max, t))
                {
                    max = t;
                }
            }

            return max;
        }

        #endregion
    }
}